Process of precipitating alkaline-earth oxalates.



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D'AVID STRAUSS, OF BASEL, SWITZERLAND, ASSIGNOR, T SOCIETY 01? CHEMICAL INDUSTRY IN BASLE, 036 BASEL, SWITZERLAND.

PROCESS PREGIPITATING ALKALINE-EARTH OXALATES.

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R's Drawing.

' To all whom it concern:

Be it known that 1, DAVID STRAUSS, chemist, a subject of the King'ofPrussia, and

-- this process a portion of the oxalic acid is lost because the approximately quantitative precipitation of the oxalic acidas calcium oxalate occurs only in the presence of very dilute solutions of alkali oxalate and when a large excess of lime :is used.

According to the present invention a sulfur. compound of an alkali-earth metal, solu- "ble in Water, as forinstance a 'monoor a polysulfid of an alkali-earth metal or the sulfhydrate' ofa monosulfid of an alkaliearth metal, is substituted for lime as precipitant ,of the oxalic acid, with the-result that the alkaline earth oxalate is precipitated even in' very concentrated solutions.

The precipitation occurs quantitatively even in solutions of the highest concentration,

' and an'excess of the precipitant is not necessary. As a lay-product a solution of alkali sulfid is obtained, which is useful as such or after evaporation.

The double decomposition is preferably "effected at the ordinary temperature, but

can also be efiected at high temperature in an autoclave.

' The' following. examples illustrate the invention, the parts being bywveight.

Example 1: 1345parts of sodium oxalate.

are dissolved in 1300 parts of water-and to the solution 166 parts of barium sulfid are added gradually, while stirring well. In

Snecification of Letters Patent. Patented June 13, 1911. Application filed March 31, 1916. Serial No. 1652341.

addition to sodium sulfid, theinsoluble barium oxalate is formed, which is filtered off,

washed and worked up in a known manner; The reaction occurs in this example according to the following equation;

COONa B coo E Q aS= BM-NaZS. Example 2: 168 parts of calcium tetrasulfid are stirred into avsolution of 134 parts of' sodium. oxalate in about 1200 parts of water: Calcium oxalate separates, while so.-

dium tetrasulfid remains in solution. The

reaction occurring in this. example is expressed. by the following equation:

COONa coo 0 s s oa N s. doom a (100 a2 4 that I claim is: 1. The described processof 'precipltating oxalic acid in the form of an insoluble alkahne; earth oxalate from solutions of alkali oxalates, which. consists in adding to the oxalate solutions one of the herein described sulfur compounds of an alkali-earth metal,

soluble in water, then filtering oil the premy name this 19th day bf March, 1910, in

the presence of two subscribing witnesses. DAVID STRAUSS. W1tnesses:

GEO. GIFFORD, AMAND BITTER. 

